In known processes for the preparation of propellant charge powders such as a dibasic POL powder from a moist raw powder, raw powder mixture is cutomarily kneaded by means of calander rollers for the purpose of homogenizing and gelatinizing or plasticizing the mixture but this can only be carried out batch-wise, not continuously. A sheet is typically formed on one of the two rollers of the calander, and this sheet must be kneaded to completion and then completely removed before a fressh batch of powder mixture can be introduced.
It is also known to carry out the kneading process continuously by means of an extruder containing kneading elements. In that case, the kneading process may be immediately followed by the moulding process within the same extruder without a break. This means that the raw powder mixture is directly converted into powder strands. It is, however, difficult to feed the correct amount of raw material into the extruder, especially if the material is made moist with water, and an even more critical difficulty is that when the powder mass is kneaded in the extruder, it is subjected to a considerable amount of heat and mechanical stress inside a closed space. This constitutes a considerable safety risk and if spontaneous ignition occurs, this inevitably results in an explosion.